t_open(3NSL) Networking Services Library Functions t_open(3NSL)NAMEt_open - establish a transport endpoint
SYNOPSIS
#include <xti.h>
#include <fcntl.h>
int t_open(const char *name, int oflag, struct t_info *info);
DESCRIPTION
This routine is part of the XTI interfaces which evolved from the TLI
interfaces. XTI represents the future evolution of these interfaces.
However, TLI interfaces are supported for compatibility. When using a
TLI routine that has the same name as an XTI routine, the tiuser.h
header file must be used. Refer to the TLI COMPATIBILITY section for
a description of differences between the two interfaces.
The t_open() function must be called as the first step in the initial‐
ization of a transport endpoint. This function establishes a transport
endpoint by supplying a transport provider identifier that indicates a
particular transport provider, that is, transport protocol, and return‐
ing a file descriptor that identifies that endpoint.
The argument name points to a transport provider identifier and oflag
identifies any open flags, as in open(2). The argument oflag is con‐
structed from O_RDWR optionally bitwise inclusive-OR'ed with O_NON‐
BLOCK. These flags are defined by the header <fcntl.h>. The file
descriptor returned by t_open() will be used by all subsequent func‐
tions to identify the particular local transport endpoint.
This function also returns various default characteristics of the
underlying transport protocol by setting fields in the t_info struc‐
ture. This argument points to a t_info which contains the following
members:
t_scalar_t addr; /* max size of the transport protocol address */
t_scalar_t options; /* max number of bytes of */
/* protocol-specific options */
t_scalar_t tsdu; /* max size of a transport service data */
/* unit (TSDU) */
t_scalar_t etsdu; /* max size of an expedited transport */
/* service data unit (ETSDU) */
t_scalar_t connect; /* max amount of data allowed on */
/* connection establishment functions */
t_scalar_t discon; /* max amount of data allowed on */
/* t_snddis() and t_rcvdis() functions */
t_scalar_t servtype; /* service type supported by the */
/* transport provider */
t_scalar_t flags; /* other info about the transport provider */
The values of the fields have the following meanings:
addr A value greater than zero (T_NULL) indicates the maxi‐
mum size of a transport protocol address and a value of
-2 (T_INVALID) specifies that the transport provider
does not provide user access to transport protocol
addresses.
options A value greater than zero (T_NULL) indicates the maxi‐
mum number of bytes of protocol-specific options sup‐
ported by the provider, and a value of -2 (T_INVALID)
specifies that the transport provider does not support
user-settable options.
tsdu A value greater than zero (T_NULL specifies the maximum
size of a transport service data unit (TSDU); a value
of zero (T_NULL) specifies that the transport provider
does not support the concept of TSDU, although it does
support the sending of a data stream with no logical
boundaries preserved across a connection; a value of -1
(T_INFINITE) specifies that there is no limit to the
size of a TSDU; and a value of -2 (T_INVALID) specifies
that the transfer of normal data is not supported by
the transport provider.
etsdu A value greater than zero (T_NULL) specifies the maxi‐
mum size of an expedited transport service data unit
(ETSDU); a value of zero (T_NULL) specifies that the
transport provider does not support the concept of
ETSDU, although it does support the sending of an expe‐
dited data stream with no logical boundaries preserved
across a connection; a value of -1 (T_INFINITE) speci‐
fies that there is no limit on the size of an ETSDU;
and a value of -2 (T_INVALID) specifies that the trans‐
fer of expedited data is not supported by the transport
provider. Note that the semantics of expedited data may
be quite different for different transport providers.
connect A value greater than zero (T_NULL) specifies the maxi‐
mum amount of data that may be associated with connec‐
tion establishment functions, and a value of -2
(T_INVALID) specifies that the transport provider does
not allow data to be sent with connection establishment
functions.
discon If the T_ORDRELDATA bit in flags is clear, a value
greater than zero (T_NULL) specifies the maximum amount
of data that may be associated with the t_snddis(3NSL)
and t_rcvdis(3NSL) functions, and a value of -2
(T_INVALID) specifies that the transport provider does
not allow data to be sent with the abortive release
functions. If the T_ORDRELDATA bit is set in flags, a
value greater than zero (T_NULL) specifies the maximum
number of octets that may be associated with the
t_sndreldata(), t_rcvreldata(), t_snddis(3NSL) and
t_rcvdis(3NSL) functions.
servtype This field specifies the service type supported by the
transport provider, as described below.
flags This is a bit field used to specify other information
about the communications provider. If the T_ORDREL‐
DATA bit is set, the communications provider supports
user data to be sent with an orderly release. If the
T_SENDZERO bit is set in flags, this indicates the
underlying transport provider supports the sending of
zero-length TSDUs.
If a transport user is concerned with protocol independence, the above
sizes may be accessed to determine how large the buffers must be to
hold each piece of information. Alternatively, the t_alloc(3NSL) func‐
tion may be used to allocate these buffers. An error will result if a
transport user exceeds the allowed data size on any function.
The servtype field of info specifies one of the following values on
return:
T_COTS The transport provider supports a connection-mode ser‐
vice but does not support the optional orderly release
facility.
T_COTS_ORD The transport provider supports a connection-mode ser‐
vice with the optional orderly release facility.
T_CLTS The transport provider supports a connectionless-mode
service. For this service type, t_open() will return -2
(T_INVALID) for etsdu, connect and discon.
A single transport endpoint may support only one of the above services
at one time.
If info is set to a null pointer by the transport user, no protocol
information is returned by t_open().
RETURN VALUES
A valid file descriptor is returned upon successful completion. Other‐
wise, a value of -1 is returned and t_errno is set to indicate an
error.
VALID STATES
T_UNINIT.
ERRORS
On failure, t_errno is set to the following:
TBADFLAG An invalid flag is specified.
TBADNAME Invalid transport provider name.
TPROTO This error indicates that a communication problem has
been detected between XTI and the transport provider
for which there is no other suitable XTI error
(t_errno).
TSYSERR A system error has occurred during execution of this
function.
TLI COMPATIBILITY
The XTI and TLI interface definitions have common names but use differ‐
ent header files. This and other semantic differences between the two
interfaces are described in the subsections below.
Interface Header
The XTI interfaces use the xti.h TLI interfaces should not use this
header. They should use the header:
#include <tiuser.h>
Error Description Values
The t_errno values TPROTO and TBADNAME can be set by the XTI interface
but cannot be set by the TLI interface.
Notes
For TLI , the t_info structure referenced by info lacks the following
structure member:
t_scalar_t flags; /* other info about the transport provider */
This member was added to struct t_info in the XTI interfaces.
When a value of -1 is observed as the return value in various t_info
structure members, it signifies that the transport provider can handle
an infinite length buffer for a corresponding attribute, such as
address data, option data, TSDU (octet size), ETSDU (octet size), con‐
nection data, and disconnection data. The corresponding structure mem‐
bers are addr, options, tsdu, estdu, connect, and discon, respectively.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│MT Level │Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOopen(2), attributes(5)SunOS 5.10 7 May 1998 t_open(3NSL)
